Re: [PATCH] sched: fix virtual-start-time update in QFQ

[David Miller <davem@davemloft.net>]

From: Paolo Valente <paolo.valente@unimore.it>
Date: Sat, 15 Sep 2012 12:41:35 +0200

> If the old timestamps of a class, say cl, are stale when the class
> becomes active, then QFQ may assign to cl a much higher start time
> than the maximum value allowed. This may happen when QFQ assigns to
> the start time of cl the finish time of a group whose classes are
> characterized by a higher value of the ratio
> max_class_pkt/weight_of_the_class with respect to that of
> cl. Inserting a class with a too high start time into the bucket list
> corrupts the data structure and may eventually lead to crashes.
> This patch limits the maximum start time assigned to a class.
> 
> Signed-off-by: Paolo Valente <paolo.valente@unimore.it>

Applied and queued up for -stable, thanks.

Please use "pkt_sched" instead of just plain "sched" in the prefixes
of your subject lines for packet scheduler changes so such changes
can be distinguished from process scheduler changes.

I fixed it up for you this time.

Thanks.